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Spriewald, S.* ; Stadler, E.* ; Hense, B.A. ; Münch, P.C.* ; McHardy, A.C.* ; Weiss, A.S.* ; Obeng, N.* ; Müller, J. ; Stecher, B.*

Evolutionary stabilization of cooperative toxin production through a bacterium-plasmid-phage interplay.

mBio 11:e00912-20 (2020)
Verlagsversion DOI
Open Access Gold
Creative Commons Lizenzvertrag
Colicins are toxins produced and released by Enterobacteriaceae to kill competitors in the gut. While group A colicins employ a division of labor strategy to liberate the toxin into the environment via colicin-specific lysis, group B colicin systems lack cognate lysis genes. In Salmonella enterica serovar Typhimurium (S. Tm), the group B colicin lb (Collb) is released by temperate phage-mediated bacteriolysis. Phage-mediated Collb release promotes S. Tm fitness against competing Escherichia coll. It remained unclear how prophage-mediated lysis is realized in a clonal population of Collb producers and if prophages contribute to evolutionary stability of toxin release in S. Tm. Here, we show that prophage-mediated lysis occurs in an S. Tm subpopulation only, thereby introducing phenotypic heterogeneity to the system. We established a mathematical model to study the dynamic interplay of S. Tm, Collb, and a temperate phage in the presence of a competing species. Using this model, we studied long-term evolution of phage lysis rates in a fluctuating infection scenario. This revealed that phage lysis evolves as bet-hedging strategy that maximizes phage spread, regardless of whether colicin is present or not. We conclude that the Collb system, lacking its own lysis gene, is making use of the evolutionary stable phage strategy to be released. Prophage lysis genes are highly prevalent in nontyphoidal Salmonella genomes. This suggests that the release of Collb by temperate phages is widespread. In conclusion, our findings shed new light on the evolution and ecology of group B colicin systems.IMPORTANCE Bacteria are excellent model organisms to study mechanisms of social evolution. The production of public goods, e.g., toxin release by cell lysis in clonal bacterial populations, is a frequently studied example of cooperative behavior. Here, we analyze evolutionary stabilization of toxin release by the enteric pathogen Salmonella. The release of colicin lb (Collb), which is used by Salmonella to gain an edge against competing microbiota following infection, is coupled to bacterial lysis mediated by temperate phages. Here, we show that phage-dependent lysis and subsequent release of colicin and phage particles occurs only in part of the Collbexpressing Salmonella population. This phenotypic heterogeneity in lysis, which represents an essential step in the temperate phage life cycle, has evolved as a bethedging strategy under fluctuating environments such as the gastrointestinal tract. Our findings suggest that prophages can thereby evolutionarily stabilize costly toxin release in bacterial populations.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter Bacteriophage ; Lysogen ; Virus ; Evolution ; Toxin ; Bacteriocin ; Regulation ; Heterogeneity ; Adaptive Dynamics ; Evolutionary Stable Strategy ; Spiteful Interaction ; Bistability ; Cheater ; Colicin ; Gastrointestinal Infection ; Phenotypic Noise; Horizontal Gene-transfer; Promotes Cooperation; Bacteriophage St64b; Induction; Stress; Gut; Diversity; Virulence; Dynamics; Survival
ISSN (print) / ISBN 2150-7511
e-ISSN 2150-7511
Zeitschrift mBio
Quellenangaben Band: 11, Heft: 4, Seiten: , Artikelnummer: e00912-20 Supplement: ,
Verlag American Society for Microbiology (ASM)
Verlagsort 1752 N St Nw, Washington, Dc 20036-2904 Usa
Begutachtungsstatus Peer reviewed
Förderungen DFG